Liquid crystal display

ABSTRACT

Provided is a liquid crystal display including an array substrate with first to third comb-shaped electrodes on a main surface thereof, a counter substrate with a common electrode that faces the first to third comb-shaped electrodes on a main surface thereof, a liquid crystal layer sandwiched between the array and counter substrates, and a color filter supported by one of the array and counter substrates and including first to third coloring layer facing the first to third comb-shaped electrodes, respectively, wherein the first comb-shaped electrode is different in shape and/or orientation from the second and third comb-shaped electrodes.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a division of and claims the benefit of priorityunder 35 USC §120 from U.S. Ser. No. 10/418,132, filed Apr. 18, 2003 nowU.S. Pat. No. 6,833,899 and is based upon and claims the benefit ofpriority under 35 USC §119 from Japanese Patent Applications No.2002-118137, filed Apr. 19, 2002; and No. 2002-126328, filed Apr. 26,2002, the entire contents of both of which are incorporated herein byreference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a liquid crystal display.

2. Description of the Related Art

A liquid crystal display, which is thin, light in weight and low inpower consumption, is used is various fields such as OA equipment, aninformation terminal, a watch and a television receiver. Particularly, aliquid crystal display equipped with a thin film transistor (TFT)exhibits a high response capability and, thus, is used as a monitor ofan apparatus that displays a large amount of information, such as aportable television receiver or a portable computer.

In recent years, demands for a picture image of high definition andshort response time are being increased, in parallel with the increaseamount of information. Of the above, high definition images areaccomplished by, for example, miniaturization of the array structureforming the TFT.

On the other hand, concerning the demand for the shortening of theresponse time, it is being studied to employ the display mode using anematic liquid crystal, such as an IPS mode, an HAN mode, an OCB mode, aπ-mode and a multi domain-type VAN (Vertical Aligned Nematic) mode, orthe display mode using a smectic liquid crystal, such as a surfacestabilized ferroelectric liquid crystal mode and an antiferroelectricliquid crystal mode, in place of the conventional display mode.

Among these display modes, the multi domain-type VAN mode permitsobtaining a response speed higher than that in the conventional TN(Twisted Nematic) mode. Also, a rubbing treatment that generatesundesired phenomena such as an electrostatic destroy is not required inthe multi domain-type VAN mode because the liquid crystal molecules areoriented in the vertical direction in the multi domain-type VAN mode.Further, the design for the compensation of the viewing angle can beachieved relatively easily in the multi domain-type VAN mode.

However, the viewing angle for the multi domain-type VAN mode is smallerthan that for the IPS mode. Naturally, it is desirable to furtherbroaden the viewing angle in the multi domain-type VAN mode.

BRIEF SUMMARY OF THE INVENTION

According to a first aspect of the present invention, there is provideda liquid crystal display, comprising an array substrate with first tothird pixel electrodes on a main surface thereof, a counter substratewith a common electrode that faces the first to third pixel electrodeson a main surface thereof, a liquid crystal layer sandwiched between thearray and counter substrates, and a color filter supported by one of thearray and counter substrates and comprising first to third coloringlayer facing the first to third pixel electrodes, respectively, whereinthe display is configured to form first and second optical regionsdifferent from each other in electric field intensity in each of firstto third pixel regions between the common electrode and the first tothird pixel electrodes when voltage is applied therebetween, the firstand second optical regions extending in a direction that is parallel tothe liquid crystal layer and alternately arranged in a direction thatcrosses a longitudinal direction of the first optical region in each ofthe first to third pixel regions, and the first pixel region beingdifferent in the longitudinal direction of the first optical region fromthe second and third pixel regions.

According to a second aspect of the present invention, there is provideda liquid crystal display, comprising an array substrate with first tothird pixel electrodes on a main surface thereof, a counter substratewith a common electrode that faces the first to third pixel electrodeson a main surface thereof, a liquid crystal layer sandwiched between thearray and counter substrates, and a color filter supported by one of thearray and counter substrates and comprising first to third coloringlayer facing the first to third pixel electrodes, respectively, whereinthe display is configured to form first and second optical regionsdifferent from each other in electric field intensity in each of firstto third pixel regions between the common electrode and the first tothird pixel electrodes when voltage is applied therebetween, the firstand second optical regions extending in a direction that is parallel tothe liquid crystal layer and alternately arranged in a direction thatcrosses a longitudinal direction of the first optical region in each ofthe first to third pixel regions, and wherein the first pixel region isdifferent in a shape of the first and/or second optical region from thesecond and third pixel regions.

According to a third aspect of the present invention, there is provideda liquid crystal display, comprising an array substrate with first tothird comb-shaped electrodes on a main surface thereof, a countersubstrate with a common electrode that faces the first to thirdcomb-shaped electrodes on a main surface thereof, a liquid crystal layersandwiched between the array and counter substrates, and a color filtersupported by one of the array and counter substrates and comprisingfirst to third coloring layer facing the first to third comb-shapedelectrodes, respectively, wherein the first comb-shaped electrode isdifferent in shape and/or orientation from the second and thirdcomb-shaped electrodes.

Where voltage is applied between the pixel electrode and the commonelectrode under the state that polarizers are arranged on the sides ofthe light source and the observer, the first optical region and thesecond optical region can be observed as regions differing from eachother in the transmittance or the reflectance. In other words, the firstand second optical regions can be confirmed by actually measuring theintensity of the electric field and/or by examining the transmittance orthe reflectance.

It is not absolutely necessary for a clear boundary to be presentbetween the first optical region and the second optical region. In otherwords, it is possible for the intensity of the electric field and themagnitudes of the transmittance or the reflectance to be changedcontinuously in the arranging direction of the first optical region andthe second optical region.

Where a clear boundary is not formed between the first optical regionand the second optical region, the sum of the width of the first opticalregion and the width of the second optical region is scarcely dependenton a boundary value, which is a value defining the boundary between thefirst and the second optical regions. However, the individual widths ofthe first and second optical regions are dependent on the boundaryvalue. It follows that, where it is necessary to obtain the boundarybetween the first optical region and the second optical region, anappropriate value such as an average value of the electric fieldintensity, the transmittance or the reflectance can be used as theboundary value.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING

FIG. 1 is a cross sectional view schematically showing the constructionof a liquid crystal display according to a first embodiment of thepresent invention;

FIG. 2 is a plan view schematically exemplifying a construction that canbe utilized in the liquid crystal display shown in FIG. 1;

FIGS. 3A to 3D schematically show the change in the orientation of theliquid crystal molecules that can be generated in the case of employingthe structure shown in FIG. 2 in the liquid crystal display shown inFIG. 1;

FIG. 4 is a plan view schematically exemplifying the construction of apixel electrode that can be utilized in the liquid crystal display shownin FIG. 1;

FIG. 5 is a plan view schematically exemplifying the construction of apixel electrode that can be utilized in the liquid crystal displayaccording to a second embodiment of the present invention;

FIG. 6 exemplifies the distribution of the transmittance that isobserved in the case of employing the construction shown in FIG. 2 inthe liquid crystal display shown in FIG. 1;

FIG. 7 is a plan view schematically exemplifying the construction thatcan be employed in the liquid crystal display shown in FIG. 1;

FIG. 8 schematically shows the change in orientation of the liquidcrystal molecules that can be generated in the case of employing theconstruction shown in FIG. 7 in the liquid crystal display shown in FIG.1;

FIGS. 9A and 9B are cross sectional views each exemplifying theconstruction that can be employed in the liquid crystal display shown inFIG. 1;

FIG. 10 is a cross sectional view schematically showing the constructionof a part of the active matrix substrate included in the liquid crystaldisplay shown in FIG. 1;

FIG. 11 is an equivalent circuit diagram of the liquid crystal displayfor Example 1 of the present invention;

FIG. 12 is a graph exemplifying the relationship between the width of aslit formed in the pixel electrode, and the transmittance; and

FIG. 13 is a graph showing the influence of the wavelength on therelationship between the width of a slit formed in the pixel electrode,and the transmittance.

DETAILED DESCRIPTION OF THE INVENTION

Embodiments of the present invention will now be described withreference to the accompanying drawings. In the accompanying drawings,the constituting elements performing the same or similar functions aredenoted by the same reference numerals so as to omit the overlappingdescription.

FIG. 1 is a cross sectional view schematically showing the constructionof a liquid crystal display 1 according to a first embodiment of thepresent invention. The liquid crystal display 1 shown in FIG. 1 is aliquid crystal display of a multi domain-type VAN mode and includes anactive matrix substrate (or an array substrate) 2 and a countersubstrate 3. The active matrix substrate 2 is bonded to the countersubstrate 3 with an adhesive layer 18 interposed therebetween such thata closed space is formed between the substrates 2 and 3. The clearancebetween the active matrix substrate 2 and the counter substrate 3 ismaintained constant by spacers 19, and the closed space formed betweenthe substrates 2 and 3 is filled with a liquid crystal materialconstituting a liquid crystal layer 4. Also, a polarizing film (orpolarizer) 5 is laminated on each surface of the liquid crystal display1.

The active matrix substrate 2 includes a transparent substrate 7 such asa glass substrate. Wirings and switching elements 8 are formed on onemain surface of the transparent substrate 7. A color filter 9 and aperipheral light shielding layer 12 are also formed on the surface ofthe transparent substrate 7. Further, pixel electrodes 10 and analignment layer 11 are formed on the color filter 9.

The wirings formed on the transparent substrate 7 include, for example,scanning lines and signal lines made of, for example, aluminum,molybdenum or copper. On the other hand, the switching elements 8 are,for example, thin film transistors (TFTs) each including a semiconductorlayer made of, for example, an amorphous silicon or a polycrystallinesilicon (polysilicon) and a metal layer made of, for example, aluminum,molybdenum, chromium, copper or tantalum, and are connected to thewirings such as scanning lines and signal lines and to the pixelelectrodes 10. The particular construction of the active matrixsubstrate 2 permits selectively applying voltage to the desired pixelelectrode 10.

The color filter 9 interposed between the transparent substrate 7 andthe pixel electrode 10 includes blue, green and red coloring layers 9B,9G and 9R. Contact holes are formed in the color filter 9 so as topermit the pixel electrodes 10 to be connected to the switching elementsvia the contact holes.

The pixel electrodes 10 are made of a transparent conductive materialsuch as ITO (Indium Tin Oxide). It is possible to form the pixelelectrodes 10 by forming first a thin film of a transparent conductivematerial by, for example, a sputtering method, followed by patterningthe thin film by employing photolithography and etching.

The alignment layer 11 is a thin film made of a transparent resin suchas polyimide. Incidentally, in the first embodiment of the presentinvention, a rubbing treatment does not performed on the alignment layer11 since the alignment layer 11 is a vertical alignment layer.

The counter substrate 3 includes a transparent substrate 15 such as aglass substrate. A common electrode 16 and an alignment layer 17 areformed successively on the transparent substrate. It is possible for thecommon electrode 16 and the alignment layer 16 to be made of thematerials equal to those used for forming the pixel electrodes 19 andthe alignment layer 11, respectively. Also, a rubbing treatment does notperformed on the alignment layer 17 since the alignment layer 17 is avertical alignment layer. Incidentally, in the first embodiment of thepresent invention, the common electrode 16 is formed in the form of aflat continuous film.

FIG. 2 is a plan view schematically exemplifying the construction thatcan be employed in the liquid crystal display shown in FIG. 1. In theconstruction shown in FIG. 2, the pixel electrode 10 includes foursections 10 a to 10 d. Slits 20 are formed in parallel at a prescribedperiod in each of the sections 10 a to 10 d. It should be noted that thesections 10 a to 10 d differ from each other in the longitudinaldirection of the slit 20. In other words, the pixel electrode 10 is acomb-shaped electrode includes the four comb-shaped sections 10 a to 10d differing from each other in the longitudinal direction of the slit20. In the liquid crystal display 1 shown in FIG. 1, the particularconstruction described above permits the pixel region to be divided intofour domains differing from each other in the tilting direction of theliquid crystal molecules in conformity with the sections 10 a to 10 d.This will now be described with reference to FIGS. 3A to 3D.

FIGS. 3A to 3D schematically show the change in the orientation of theliquid crystal molecules that is brought about in the case of employingthe construction shown in FIG. 2 in the liquid crystal display shown inFIG. 1. Incidentally, FIGS. 3A and 3C are plan views, and FIGS. 3B and3D are side views showing the constructions shown in FIGS. 3A and 3Cobserved from the lower sides in the drawings, respectively. Also, someof the constituting elements are omitted in FIGS. 3A to 3D for the sakeof simplicity.

Where a voltage is not applied between the pixel electrode 10 and thecommon electrode 16, the alignment layers 11 and 17 serve to permitliquid crystal molecules 25, which form the liquid crystal layer 4 andhave a negative dielectric anisotropy in the present embodiment, to beoriented in the vertical direction. As a result, the liquid crystalmolecules 25 are oriented such that the major axes of the liquid crystalmolecules are rendered substantially perpendicular to the film surfaceof the alignment layer 11.

If a relatively low first voltage is applied between the pixel electrode10 and the common electrode 16, a leakage electric field is generatedabove the slit 20 of the pixel electrode 10. As a result, the electricflux lines are inclined as shown in FIG. 3B.

The electric field generated by application of voltage between the pixelelectrode 10 and the common electrode 16 serves to permit the liquidcrystal molecules 25 to be oriented in a direction perpendicular to theelectric flux line. It follows that the liquid crystal molecules 25 areoriented as shown in FIG. 3A by the effects of the alignment layers 11,17 and the electric field.

However, under the sate shown in FIG. 3A, an interference is broughtabout between the orienting state of the liquid crystal molecules on theright side and the orienting state of the liquid crystal molecules 25 onthe left side. As a result, the tilting direction of the liquid crystalmolecules 25 is changed upward or downward in the drawing so as toassume a more stable alignment state.

Suppose the portion sandwiched between a pair of slits 20 of the pixelelectrode 10 or the region in the vicinity of the particular portion isshaped symmetrical or isotropic in the up-down direction in the drawing,as shown in FIG. 3A. In this case, the probability for the tiltingdirection of the liquid crystal molecules 25 to be changed upward asdenoted by an arrow 31 is rendered equal to the probability for thetilting direction of the liquid crystal molecules 25 to be changeddownward as denoted by an arrow 32.

On the other hand, where the portion sandwiched between the pair of theslits 20 of the pixel electrode 10 and the region in the vicinity of theparticular portion is asymmetric or anisotropic in the up-down directionin the drawing, as shown in FIG. 3C, the electric flux lines arerendered asymmetric between the both edge portions of the pixelelectrode 10. The electric flux lines are also rendered asymmetricbetween the both edge portions of the slit 20. As a result, thealignment state in which the liquid crystal molecules 25 are oriented inthe direction denoted by the arrow 32 is rendered more stable than thealignment state in which the liquid crystal molecules 25 are oriented inthe direction denoted by the arrow 31. It follows that the averagetilting direction (director) of the liquid crystal molecules 25 extendsdownward as denoted by an arrow 32 in FIG. 3C.

If the voltage applied between the pixel electrode 10 and the commonelectrode 16 is increased to a second voltage higher than the firstvoltage, the effect of the electric field on the orientation of theliquid crystal molecules 25, i.e., the force to make the liquid crystalmolecules 25 oriented in the direction perpendicular to the electricflux line, becomes much greater than the effect of the alignment layers11 and 17 on the orientation of the liquid crystal molecules 25, i.e.,the force to make the liquid crystal molecules 25 oriented in thevertical direction. It follows that the liquid crystal molecules 25 arecaused to change the tilting angle toward the horizontal orientation.

It should be noted that, even where the second voltage is appliedbetween the pixel electrode 10 and the common electrode 16, thealignment state in which the liquid crystal molecules 25 are oriented inthe direction denoted by the arrow 32 is more stable than the alignmentstate in which the liquid crystal molecules 25 are oriented in thedirection denoted by the arrow 31 as in the case where the first voltageis applied between the pixel electrode 10 and the common electrode 16.It follows that, in the case where the voltage applied between the pixelelectrode 10 and the common electrode 16 is changed within a range ofbetween the first voltage and the second voltage, the director of theliquid crystal molecules 25 is changed within a plane perpendicular tothe arranging direction of the slits 20. In other words, where thevoltage applied between the pixel electrode 10 and the common electrode16 is changed within a range of between the first voltage and the secondvoltage, the liquid crystal molecules 25 are caused to change thetilting angle while maintaining the average tilting direction within aplane perpendicular to the arranging direction of the slits 20.

Therefore, by allowing the four sections 10 a to 10 d to differ fromeach other in the longitudinal direction of the slit 20, it is possibleto change the tilting angle while maintaining the tilting direction ofthe liquid crystal molecules 25 as shown in FIG. 2. In other words, itis possible to form in a single pixel region four domains, differingfrom each other in the tilting direction of the liquid crystal molecules25, only by a structure of the active matrix substrate 2. Also, in thefirst embodiment of the present invention, it is possible to change thetilting angle while maintaining the average tilting direction of theliquid crystal molecules 25 within a plane perpendicular to thearranging direction of the slits 20, with the result that it is possibleto achieve a high response speed. In addition, an alignment defect isunlikely to take place, and formation of domains in a pixel region takesplace satisfactorily.

In the first embodiment of the present invention, one of the pixelelectrode 10 facing the blue coloring layer 9B, the pixel electrode 10facing the green coloring layer 9G and the pixel electrode 10 facing thered coloring layer 9R differs from the other two pixel electrodes 10 inthe longitudinal direction of the slit 20. In the case of employing theparticular construction, it is possible to achieve a wide viewing angle,as described in the following.

FIG. 4 is a plan view schematically exemplifying the construction of thepixel electrode that can be employed in the liquid crystal display shownin FIG. 1. Incidentally, FIG. 4 depicts the coloring layers 9B, 9G and9R and the pixel electrode 10 alone among the construction that isobserved when the liquid crystal display 1 is viewed perpendicularly tothe main surface of the liquid crystal display 1. Also, the pixelelectrodes 10 corresponding to the coloring layers 9B, 9G and 9R aredenoted by reference numerals 10B, 10G and 10R, respectively.

When, for example, the second voltage is applied between the pixelelectrode 10 and the common electrode 16, the liquid crystal layer 4performs the function similar to that performed by a λ/2 retardationplate. Therefore, in order to achieve a wide viewing angle, it isdesirable for the observing angle dependence of the phase differencebetween a pair of linearly polarized lights, which is imparted by theliquid crystal layer 4, to be rendered substantially constant in respectof the light of all the wavelengths, so as to suppress the change in thedisplayed color in accordance with the observing angle.

The phase difference between a pair of linearly polarized lights, whichis imparted by the liquid crystal layer 4, is proportional to therefractive index anisotropy Δn of the liquid crystal material and to theoptical path length d, and is inversely proportional to the wavelengthλ. Generally, it is difficult to change the optical path length d inaccordance with the wavelength λ. Therefore, in order to render theobserving angle dependence of the phase difference between a pair oflinearly polarized lights, which is imparted by the liquid crystal layer4, substantially constant in respect of the light of all thewavelengths, it is necessary to use a liquid crystal material having aconstant ratio of the refractive index anisotropy Δn to the wavelengthλ. However, it is impractical to use such a liquid crystal material.

On the other hand, in the construction shown in FIG. 4, the pixelelectrode 10B, the pixel electrode 10G and the pixel electrode 10R aremade different from each other in the longitudinal direction of theslits 20. Where at least two of the pixel electrodes 10B, 10G and 10Rcorresponding to the coloring layers 9B, 9G and 9R, respectively, arerendered different from each other in the longitudinal direction of theslit 20, at least two of the pixel regions corresponding to the pixelelectrodes 10B, 10G and 10R are rendered different from each other inthe tilting directions of the liquid crystal molecules. As a result, atleast two of the pixel regions corresponding to the pixel electrodes10B, 10G and 10R are rendered different from each other in the slowphase axis of the liquid crystal layer 4.

The phase difference generated by the passage of a pair of linearlypolarized lights through the liquid crystal layer 4 and the observingangle dependence of the phase difference are changed in accordance withthe angle made between the polarization plane of the linearly polarizedlight incident on the liquid crystal layer 4 and the slow phase axis ofthe liquid crystal layer 4. Also, the pixel regions corresponding to thepixel electrodes 10B, 10G and 10R play the role of modulating the lightrays differing from each other in the wavelength. Therefore, by settingappropriately the angle made between the longitudinal directions of theslits 20 and by setting appropriately the angle made between thetransmission easy axis of the polarizing film 5 and the longitudinaldirection of the slit 20 for at least two of the pixel electrodes 10B,10G and 10R, it becomes possible to suppress the change in the displayedcolor in accordance with the observing angle. In other words, it ispossible to achieve a wide viewing angle.

In the first embodiment of the present invention, the effect describedabove can be obtained, if at least two of the pixel electrodes 10B, 10Gand 10R are different from each other in the longitudinal direction ofthe slit 20. In general, the effect is rendered prominent in the casewhere the difference between the longitudinal direction of the slit 20is at least 5°.

In the first embodiment of the present invention, it suffices for one ofthe pixel electrodes 10B, 10G, 10R to be different from the other pixelelectrodes in the longitudinal direction of the slit 20. However, it ispossible for the pixel electrodes 10B, 10G, 10R to be different fromeach other in the longitudinal directions of the slits 20.

In the first embodiment of the present invention, it is desirable to setat about 45° the angle made between the longitudinal direction of theslit 20 formed in one of the pixel electrodes 10B, 10G, 10R and thetransmission easy axis of one of the polarizing films 5. The anglereferred to above is advantageous for achieving a high transmittance.

For example, where the angle made between the transmission easy axis ofone of the polarizing film 5 and the longitudinal direction of the slit20 formed in the pixel electrode 10R is set at about 45°, it is possibleto set the angle made between the transmission easy axis noted above andthe longitudinal direction of the slit 20 formed in the pixel electrode10B at an angle deviated from 45°, and to set the angle made between thetransmission easy axis noted above and the longitudinal direction of theslit 20 formed in the pixel electrode 10G at an angle less deviated from45°.

Also, where the angle made between the transmission easy axis of one ofthe polarizing film 5 and the longitudinal direction of the slit 20formed in the pixel electrode 10G is set at about 45°, it is possible toset the deviation of the angle made between the transmission easy axisnoted above and the longitudinal direction of the slit 20 formed in thepixel electrode 10B from 45° substantially equal to the deviation of theangle made between the transmission easy axis noted above and thelongitudinal direction of the slit 20 formed in the pixel electrode 10Rfrom 45°.

Further, where the angle made between the transmission easy axis of oneof the polarizing film 5 and the longitudinal direction of the slit 20formed in the pixel electrode 10B is set at about 45°, it is possible toset the angle made between the transmission easy axis noted above andthe longitudinal direction of the slit 20 formed in the pixel electrode10R at an angle deviated from 45°, and to set the angle made between thetransmission easy axis noted above and the longitudinal direction of theslit 20 formed in the pixel electrode 10G at an angle less deviated from45°.

Among the cases exemplified above, it is desirable to set the angle madebetween the transmission easy axis of one of the polarizing films 5 andthe longitudinal direction of the slit 20 formed in the pixel electrode10G at about 45°. In this case, it is possible to obtain the greatesteffect of suppressing the change in the displayed color in accordancewith the observing angle.

As described above, in the first embodiment of the present invention,first and second optical regions differing from each other in theintensity of the electric field are formed in the pixel region withinthe liquid crystal layer 4 when a prescribed voltage is applied betweenthe pixel electrode 10 and the common electrode 16 such that theseoptical regions extend in one direction and are alternately arrangedrepeatedly in the direction crossing the extending direction. Also, inthe first embodiment of the present invention, one of the pixel regionfacing the blue coloring layer 9B, the pixel region facing the greencoloring layer 9G and the pixel region facing the red coloring layer 9Ris made different from the other two pixel regions in the longitudinaldirection of the first or second optical region. As a result, it ispossible to suppress the change of the displayed color in accordancewith the viewing angle so as to make it possible to achieve a wideviewing angle.

In other words, according to the first embodiment of the presentinvention, it is possible to provide a liquid crystal display capable ofrealizing a wide viewing angle in the case of utilizing a multidomain-type VAN mode.

A second embodiment of the present invention will now be described. Theliquid crystal display according to the second embodiment of the presentinvention is equal to the liquid crystal display 1 according to thefirst embodiment of the present invention, except that the secondembodiment differs from the first embodiment in the construction of thepixel electrode 10.

As already described in conjunction with the first embodiment, theliquid crystal layer 4 plays the role similar to that played by a λ/2retardation plate when, for example, a second voltage is applied betweenthe pixel electrode 10 and the common electrode 16. Therefore, in orderto achieve a wide viewing angle, it is desirable for the observing angledependence of the phase difference between a pair of linearly polarizedlights, which is imparted by the liquid crystal layer 4, to be renderedsubstantially constant in respect of the light of all the wavelengths,so as to suppress the change in the displayed color in accordance withthe observing angle.

In the second embodiment of the present invention, the pixel regionscorresponding to the pixel electrodes 10B, 10G and 10R are rendereddifferent from each other in the shape of the first and/or secondoptical regions. In a typical case, the comb-shaped pixel electrodes10B, 10G and 10R are rendered different from each other in the ratio ofthe width and/or area of the comb-teeth portion to the slit 20. In thiscase, it is possible to allow the pixel regions corresponding to thepixel electrodes 10B, 10G and 10R to be different from each other in thedensity of the electric flux lines, i.e., the intensity of the electricfield. It follows that it is possible to allow these pixel regions to bedifferent from each other in the tilting angle of the liquid crystalmolecules 25.

The situation that the pixel regions corresponding to the pixelelectrodes 10B, 10G and 10R differ from each other in the tilting angleof the liquid crystal molecule 25 implies that the pixel regions notedabove also differ from each other in the effective refractive indexanisotropy Δn of the liquid crystal material. Also, the phase differencebetween a pair of linearly polarized lights, which is imparted by theliquid crystal layer 4, is proportional to the refractive indexanisotropy Δn of the liquid crystal material. It follows that theobserving angle dependence of the phase difference between a pair oflinearly polarized lights, which is imparted by the liquid crystal layer4, can be rendered substantially constant in respect of the light of allthe wavelengths, by appropriately setting the shape of the first and/orsecond optical regions. In other words, it is possible to suppress thechange in the displayed color in accordance with the observing angle soas to achieve a wide viewing angle.

FIG. 5 is a plan view schematically exemplifying the construction of thepixel electrode that can be utilized in the liquid crystal display 1according to the second embodiment of the present invention.Incidentally, FIG. 5 depicts the coloring layers 9B, 9G and 9R and thepixel electrode 10 observed when the liquid crystal display 1 is viewedperpendicularly to the main surface of the liquid crystal display 1.Also, the pixel electrodes 10 corresponding to the coloring layers 9B,9G and 9R are denoted by reference numerals 10B, 10G and 10R,respectively.

The construction shown in FIG. 5 is substantially equal to theconstruction shown in FIG. 4 except the aspect pointed out below.Specifically, in the construction shown in FIG. 4, the comb-shaped pixelelectrode 10G differs in orientation from each of the comb-shaped pixelelectrodes 10B and 10R. On the other hand, in the construction shown inFIG. 5, the comb-shaped pixel electrodes 10B, 10G and 10R are equal inorientation to each other. Also, in the construction shown in FIG. 4,the pixel electrodes 10B, 10G and 10R are equal in the width of the slit20 to each other. In the construction shown in FIG. 5, however, thewidth W_(2G) of the slit 20 formed in the pixel electrode 10G, the widthW_(2B) of the slit 20 formed in the pixel electrode 10B, and the widthW_(2R) of the slit 20 formed in the pixel electrode 10R differ from eachother.

Where at least two of the pixel electrodes 10B, 10G and 10Rcorresponding to the coloring layers 9B, 9G and 9R differ from eachother in the width of the slit 20 as described above, the pixel regionscorresponding to the pixel electrodes 10B, 10G and 10R are rendereddifferent from each other in the tilting angle of the liquid crystalmolecules, i.e., in the effective refractive index anisotropy Δn of theliquid crystal material. As a result, it is possible to suppress thechange in the displayed color in accordance with the observing angle.

In the second embodiment of the present invention, the particular effectdescribed above can be obtained, if at least two of the pixel electrodes10B, 10G and 10R are rendered different from each other in the width W₂of the slit 20. It is also possible to obtain the particular effectdescribed above in the case where at least two of the pixel electrodes10B, 10G and 10R are rendered different from each other in the width ofthe comb-teeth portion. Further, the particular effect can be obtainedin the case where at least two of the pixel electrodes 10B, 10G and 10Rare rendered different from each other in both the width of thecomb-teeth portion and the width of the slit 20.

In the second embodiment of the present invention, it suffices for oneof the pixel electrodes 10B, 10G and 10R to differ from the other pixelelectrodes in the shape for obtaining the particular effect. Of course,it is possible for all three pixel electrodes 10B, 10G and 10R to differfrom each other in shape.

As described above, in the second embodiment of the present invention,first and second optical regions differing from each other in theintensity of the electric field are formed in the pixel region withinthe liquid crystal layer 4 when a prescribed voltage is applied betweenthe pixel electrode 10 and the common electrode 16 such that theseoptical regions extend in one direction and are alternately arrangedrepeatedly in the direction crossing the extending direction. Also, inthe second embodiment of the present invention, one of the pixel regionfacing the blue coloring layer 9B, the pixel region facing the greencoloring layer 9G and the pixel region facing the red coloring layer 9Ris made different from the other two pixel regions in the shape of thefirst and/or second optical region. As a result, it is possible tosuppress the change of the displayed color in accordance with theviewing angle so as to make it possible achieve a wide viewing angle.

In other words, according to the second embodiment of the presentinvention, it is possible to provide a liquid crystal display capable ofrealizing a wide viewing angle in the case of utilizing a multidomain-type VAN mode.

The techniques described above in conjunction with the first and secondembodiments of the present invention can be utilized in combination. Forexample, in the construction shown in FIG. 4, it is possible for thepixel electrodes 10B, 10G and 10R to be made different from each otherin the width of the slit 20.

In each of the first and second embodiments of the present invention,the image display is performed by controlling the opticalcharacteristics of the liquid crystal layer 4, and the opticalcharacteristics of the liquid crystal layer 4 are controlled by forminga plane wave-like distribution in the intensity of a electric fieldwithin the pixel region and by changing the intensity of the electricfield. The formation of such a distribution in the intensity of theelectric field can be actually confirmed by, for example, applyingvoltage to the pixel electrode 10 under the state that the countersubstrate 3 is removed from the active matrix substrate 2. It is alsopossible to confirm the formation of the distribution in the intensityof the electric field by the method described below.

In performing the control described above, an electric field having anintensity higher than that in the portion on the slit 20 is formed in aportion on the pixel electrode 10 in the liquid crystal layer 4. As aresult, the liquid crystal molecules 25 in the portion on the pixelelectrode 10 are inclined more greatly than the liquid crystal molecules25 in the portion on the slit 20. In other words, the portion on thepixel electrode 10 and the portion on the slit 20 in the liquid crystallayer 4 are rendered different from each other in the average tiltingangle of the liquid crystal molecules 25. Such a difference in thetilting angle can be observed as an optical difference.

FIG. 6 exemplifies the distribution of the transmittance that isobserved in the case of employing the construction shown in FIG. 2 inthe liquid crystal display shown in FIG. 1. Incidentally, FIG. 6 showsthe plane wave-like distribution of the transmittance that is observedin the case where a third voltage, intermediate between the first andsecond voltages, is applied between the pixel electrode 10 and thecommon electrode 16 under the state that a polarizer (or a polarizingfilm) is arranged on the side of each of the light source and theobserver relative to the liquid crystal layer 4. It follows that,according to the first and second embodiments of the present invention,the characteristics described above with reference to FIGS. 1 to 5 canbe observed as the optical characteristics.

In the construction described above with reference to FIGS. 2 to 6, thewidth of the slit 20 is set constant in the longitudinal direction ofthe slit 20. However, it is possible for the width of the slit 20 to bechanged in the longitudinal direction of the slit 20.

FIG. 7 is a plan view schematically exemplifying the construction thatcan be employed in the liquid crystal display shown in FIG. 1. On theother hand, FIG. 8 schematically shows the change in the orientation ofthe liquid crystal molecules that is brought about in the case ofemploying the construction shown in FIG. 7 in the liquid crystal displayshown in FIG. 1. Incidentally, the section 10 a alone of the foursections 10 a to 10 d is depicted in FIG. 7, and only a part of thesection 10 a shown in FIG. 6 is depicted in FIG. 8.

In the construction shown in FIGS. 7 and 8, the width of the slit 20 iscontinuously increased from the central portion of the pixel electrode10 toward the peripheral portion. According to the particularconstruction, alignment of liquid crystal induces the director to beoriented in the direction denoted by arrows 32 in not only an upper endof the comb-teeth portion but also side ends of the comb-teeth portionas shown in FIG. 8. It follows that the construction shown in FIGS. 7and 8 permits further improving the transmittance and the responsespeed.

In the description given above, distribution of the electric fieldintensity, in which regions having a low intensity and regions having ahigh intensity are alternately arranged periodically, is generated ineach domain by forming the slit 20 in the pixel electrode 10. If theslit 20 is used for forming the distribution of the electric fieldintensity, a relatively high degree of freedom in design is possible.However, the electric field distribution can also be generated byanother method. Examples will now be described with reference to FIGS.9A and 9B.

FIGS. 9A and 9B are cross sectional views each schematicallyexemplifying the construction that can be utilized in the liquid crystaldisplay shown in FIG. 1.

In the construction shown in FIG. 9A, a dielectric layer 21 that ispatterned like the slits 20 is formed on the pixel electrode 10 in placeof forming the slits 20 on the pixel electrode 10. In this case, aregion having an electric field of a lower intensity can be formed abovethe dielectric layer 21 if a material having a dielectric constant lowerthan that of the liquid crystal material such as an acrylic resin, anepoxy resin or a novolak resin is used for forming the dielectric layer21. It follows that it is possible to obtain an effect similar to thatobtained in the case of forming the slit 20.

On the other hand, in the construction shown in FIG. 9B, a wiring 23 isformed on the pixel electrode 10 with a transparent insulating layer 22interposed therebetween in place of forming the slit 20 on the pixelelectrode 10. The wiring 23, which forms, for example, a signal line, agate line or an auxiliary capacitance line, is arranged in a patternsimilar to that of the slit 20. According to the construction, a regionhaving an electric field of a higher intensity can be formed above thewiring 23. It follows that it is also possible in this case to obtain aneffect similar to that obtained in the case of forming the slit 20.

Incidentally, in the case where the liquid crystal display 1 is of atransmission type, it is desirable in terms of the transmittance to usea transparent material for forming the dielectric layer 21 and thewiring 23. Also, where the liquid crystal display 1 is of a reflectiontype, it is possible to use an opaque material, such as a metallicmaterial, in addition to the transparent material for forming thedielectric layer 21 and the wiring 23.

In each of the first and second embodiments of the present inventiondescribed above, it is desirable for the sum W₁₂ of the width W₁ of theregion having an electric field of a higher intensity and the width W₂of the region having an electric field of a lower intensity within theliquid crystal layer 4 to be not larger than 20 μm. If the sum W₁₂ ofthe widths W₁ and W₂ noted above is not larger than 20 μm, it ispossible to control the orientation of the liquid crystal moleculesdescribed above, so as to make it possible to achieve a sufficientlyhigh transmittance. Also, it is desirable for the sum W₁₂ noted above tobe not smaller than 6 μm. If the sum W₁₂ is not smaller than 6 μm, it ispossible in general to form the structure that permits forming regionshaving an electric field of a higher intensity and regions having anelectric field of a lower intensity within the liquid crystal layer 4 ata sufficiently high precision. In addition, it is possible to achievealignment of the liquid crystal with a higher stability.

Incidentally, the sum W₁₂ noted above is substantially equal to the sumof the width of the comb-teeth portion of the pixel electrode 10 that issandwiched between the adjacent slits 20 and the width of the slit 20,the sum of the width of the portion sandwiched between the adjacentdielectric layers 21 and the width of the dielectric layer 21, the sumof the width of the wiring 23 formed on the pixel electrode 10 and thewidth of the region sandwiched between the adjacent wirings 23, the sumof the width of the region having a larger tilting angle and the widthof the region having a smaller tilting angle during application of thethird voltage, or the sum of the width of the region having a highertransmittance and the width of the region having a lower transmittanceduring application of the third voltage. It follows that it is alsodesirable for each of the sums of the widths noted above to be notlarger than 20 μm and to be not smaller than 6 μm.

In each of the first and second embodiments of the present invention, itis desirable for each of the width W₁ and the width W₂ to be not largerthan 8 μm. It is also desirable for each of the width W₁ and the widthW₂ to be not smaller than 4 μm. Where each of the width W₁ and the widthW₂ falls within a range of between 4 μm and 8 μm, a sufficiently highperformance in practice can be expected in respect of the response speedand the transmittance.

Incidentally, the width W₁ and the width W₂ noted above correspond tothe width of the comb-teeth portion of the pixel electrode 10 that issandwiched between the adjacent slits 20 and the width of the slit 20,the width of the region sandwiched between the adjacent dielectriclayers 21 and the width of the dielectric layer 21, the width of thewiring 23 formed on the pixel electrode 10 and the width of the regionsandwiched between the adjacent wirings 23, the width of the regionhaving a larger tilting angle and the width of the region having asmaller tilting angle during application of the third voltage, and thewidth of the region having a higher transmittance and the width of theregion having a lower transmittance during application of the thirdvoltage, respectively. It follows that it is also desirable for each ofthe widths noted above to be not larger than 8 μm and to be not smallerthan 4 μm.

In each of the first and second embodiments of the present invention,the length of the region having an electric field of a higher intensityand the length of the region having an electric field of a lowerintensity within the liquid crystal layer 4 should be larger than thewidth W₁ and the width W₂, respectively. Also, it is desirable for eachof the lengths noted above to be at least twice the width W₁₂, which isthe sum of the widths W₁ and W₂. In this case, it is possible to permitmore liquid crystal molecules to be oriented in the longitudinaldirection of each of these regions.

In each of the first and second embodiments of the present inventiondescribed above, both the region having an electric field of a higherintensity and the region having an electric field of a lower intensityin the liquid crystal layer 4 are formed asymmetric in the up-downdirection, as shown in FIG. 3C. Alternatively, it is possible for theseregions to be formed symmetric in the up-down direction as shown in FIG.3A. The former case is advantageous over the latter case in terms of,for example, the response speed.

In each of the first and second embodiments of the present inventiondescribed above, employed is a VAN mode in which nematic liquid crystalmolecules having a negative dielectric anisotropy are verticallyaligned. Alternatively, it is also possible to use nematic liquidcrystal molecules having a positive dielectric anisotropy. Particularly,where a high contrast is desired, it is possible to achieve a highcontrast not lower than, for example, 400:1 and a brighter screen designbased on a high transmittance design, by employing a VAN mode and anormally black mode.

In each of the first and second embodiments of the present inventiondescribed above, the shapes of the sections 10 a to 10 d collectivelyconstituting the pixel electrode 10 are not particularly limited. Forexample, it is possible for each of the sections 10 a to 10 d to berectangular or to be fan-shaped.

In each of the first and second embodiments of the present inventiondescribed above, the pixel electrode 10 is formed of a plurality ofsections 10 a to 10 d. Alternatively, where it is not desired to dividea single pixel region into a plurality of domains differing from eachother in the tilting direction of the liquid crystal molecules, it ispossible for the pixel electrode to be formed of a single region alone.Incidentally, where a single pixel region includes a plurality ofcombinations of the region having an electric field of a higherintensity and the region having an electric field of a lower intensity,it is desirable for the regions having an electric field of a higherintensity or the region having an electric field of a lower intensity,which are included in the adjacent combinations, to be parallel and/orperpendicular to each other, and to differ from each other in thedirector of the liquid crystal molecules contained in the liquid crystallayer 4 during the voltage application.

In each of the first and second embodiments of the present inventiondescribed above, the structure, which permits forming a region having anelectric field of a higher intensity and a region having an electricfield of a lower intensity within the liquid crystal layer duringapplication of the third voltage, is formed only in the active matrixsubstrate 2. However, it is possible to form a structure in each of theactive matrix substrate 2 and the counter substrate 3 in order to form aregion having an electric field of a higher intensity and a regionhaving an electric field of a lower intensity within the liquid crystallayer during application of the third voltage. It should be noted inthis connection that, in the former case, high precision positioningutilizing, for example, an alignment mark is rendered unnecessary informing a cell by bonding the active matrix substrate 2 to the countersubstrate 3.

Further, in each of the first and second embodiments of the presentinvention described above, employed is the structure in which colorfilter 9 is disposed on the active matrix substrate 2. However, it isalso possible to dispose the color filter 9 on the counter substrate 3.It should be noted in this connection that, in the former case, highprecision positioning utilizing, for example, an alignment mark isrendered unnecessary in forming a cell by bonding the active matrixsubstrate 2 to the counter substrate 3.

Some examples of the present invention will now be described.

EXAMPLE 1

A liquid crystal display 1 as shown in FIG. 1 was manufactured asfollows. In this Example, the pixel electrodes 10B, 10G and 10R havingplanar shapes, as shown in FIG. 4, were formed as the pixel electrode10.

FIG. 10 is a cross sectional view schematically showing the constructionof a part of the active matrix substrate 2 included in the liquidcrystal display 1 shown in FIG. 1. In this Example, the active matrixsubstrate 2 shown in FIG. 10 was prepared first as follows.

First, an undercoat layer 40 was formed on a glass substrate 7. Then, apolysilicon layer was formed on the undercoat layer 40, followed bypatterning the polysilicon layer and subsequently doping the patternedpolysilicon layer with an impurity. As a result, formed were a channelregion 41 as a semiconductor layer of a TFT 8, a drain region 42 and asource region 43 each doped with an impurity, and an auxiliary capacitorelectrode 44. Then, a gate insulator 45 was formed to cover the channelregion 41, the drain region 42, the source region 43 and the auxiliarycapacitor electrode 44. Incidentally, contact holes were formed in thegate insulator 45 in the positions corresponding to the drain region 42,the source region 43 and the auxiliary capacitor electrode 44.

Next, a scanning line 46, which serves as a gate electrode, too, and anauxiliary capacitor line 47 were formed on the gate insulator 45,followed by forming an interlayer insulating film 48 in a manner tocover the scanning line 46 and the auxiliary capacitor line 47. Acontact hole communicating with the contact hole of the gate insulator45 was formed in the interlayer insulating film 48. Then, a signal line49, which serves as a drain electrode, too, a source electrode 50, and acontact electrode 51 were formed on the interlayer insulating film 48.

Incidentally, the signal line 49 was arranged to cross each of thescanning line 46 and the auxiliary capacitor line 47 at substantialright angles. The auxiliary capacitor line 47 was insulated from thecontact electrode 51. In this case, a molybdenum-tungsten was used forforming each of the scanning line 46 and the auxiliary capacitor line47. On the other hand, an aluminum-based material was used for formingthe signal line 49.

Next, the color filter 9 and the peripheral light shielding layer 12were formed on the surface of the resultant structure. To be morespecific, the surface of the substrate 7 on which the TFT 8, etc. wasformed was coated with an ultraviolet-curing acrylic resin resist havinga red pigment dispersed therein, by using a spinner. Then, the coatedresin resist film was dried at 90° C. for 100 minutes, followed byirradiating the portion of the coated film, in which a red coloringlayer 9R is to be formed, with ultraviolet light having a wavelength of365 nm at an intensity of 100 mJ/cm². The irradiation of the coated filmwith with ultraviolet light was performed via a prescribed photomask.Then, the coated film was subjected to a developing treatment for 20seconds by using a 1% aqueous solution of KOH so as to form a redcoloring layer 9R having a thickness of 3.2 μm. Further, a greencoloring layer 9G and a blue coloring layer 9B were successively formedby a method similar to that above for forming the red coloring layer 9R.A baking treatment was then applied at 200° C. for 60 minutes so as toobtain a color filter 9 including the red, green and blue coloringlayers 9R, 9G and 9B.

Incidentally, the wavelength of the visible light exhibiting the highesttransmittance, i.e., the maximum transmission wavelength, of the redcoloring layer 9R was found to be 620 nm. Also, the maximum transmissionwavelength of the green coloring layer 9G was found to be 550 nm, andthe maximum transmission wavelength of the blue coloring layer 9B wasfound to be 440 nm. Also, contact holes for connecting the pixelelectrode 10 to the source electrode 50 and to the auxiliary capacitorelectrode 51 were formed in the color filter 9. Further, the blue, greenand red coloring layers 9B, 9G and 9R constituting the color filter 9were allowed to partially overlap with each other so as to form spacer19 shown in FIG. 1.

Next, an ITO layer was formed to a thickness of 150 nm on the colorfilter 9 by a sputtering method via a mask of a prescribed pattern.Then, a resist pattern was formed on the ITO film, and the exposedportion of the ITO film was etched by using the resist pattern as amask. In this fashion, the pixel electrodes 10B, 10G and 10R shown inFIG. 4 were formed as the pixel electrode 10. Incidentally, the width W₂of the slit 20 was set at 5 μm, and the width W₁ of the portion of thepixel electrode 10 that was sandwiched between the adjacent slits 20,i.e., the comb-teeth portion, was also set at 5 μm.

Then, the entire surface of the glass substrate 7 on which the pixelelectrode 10 was formed was coated with a thermosetting resin, followedby baking the coated film so as to form a vertical alignment layer 11having a thickness of 70 nm. In this fashion, preparation of the activematrix substrate 2 was finished.

Next, an ITO film was formed as a common electrode 16 by a sputteringmethod on one main surface of another glass substrate 15. Then, avertical alignment layer 17 was formed on the entire surface of thecommon electrode 16 by a method similar to that used for preparation ofthe active matrix substrate 2. In this fashion, preparation of a countersubstrate 3 was finished.

Then, the active matrix substrate 2 was bonded to the counter substrate3. To be more specific, the peripheral portion of the active matrixsubstrate 2 was aligned with the peripheral portion of the countersubstrate 3 such that the alignment layer 11 formed on the active matrixsubstrate 2 was faced the alignment layer 17 formed on the countersubstrate 17. Under this condition, the active matrix substrate 2 wasbonded to the counter substrate 3 with a thermosetting epoxy resinadhesive layer 18 interposed therebetween, in a manner to leave aninjection port for injecting a liquid crystal material into a free spacedefined by the active matrix substrate 2, the counter substrate 3 andthe thermosetting epoxy resin adhesive 18. Then, the resultant structurewas heated so as to form a liquid crystal cell. Incidentally, the cellgap of the liquid crystal cell was maintained constant by using thespacer 19 having a height of 4 μm. Also, in bonding the active matrixsubstrate 2 to the counter substrate 3, the edge portions of the activematrix substrate 2 and the counter substrate 3 were aligned so as toposition the active matrix substrate 2 and the counter substrate 3. Inother words, high precision positioning utilizing, for example, analignment mark, was not performed. Further, a conductive material layer,such as a silver paste layer, was formed on the terminal arrangedoutside the area of the active matrix substrate 2 surrounded by theadhesive layer 18, so as to connect the terminal to the common electrode16.

Next, a fluorine-series liquid crystal material having a negativedielectric anisotropy was injected into the liquid crystal cell by astandard method, so as to form a liquid crystal layer 4. Then, theliquid crystal injection port was sealed with an ultraviolet-curingresin, and polarizing films 5 were attached to both surfaces of theliquid crystal cell so as to obtain the liquid crystal display 1 shownin FIG. 1.

Incidentally, the transmission easy axis of one of the polarizing films5 was perpendicular to the transmission easy axis of the otherpolarizing film 5. Also, the angle made between the longitudinaldirection of the slit 20 formed in the pixel electrode 10G and thetransmission easy axis of one of the polarizing films 5 and the anglemade between the longitudinal direction of the slit 20 formed in thepixel electrode 10G and the transmission easy axis of the otherpolarizing film 5 were set at 45° and 135°, respectively. Also, theangle made between the longitudinal direction of the slit 20 formed inthe pixel electrode 10B and the transmission easy axis of one of thepolarizing films 5 and the angle made between the longitudinal directionof the slit 20 formed in the pixel electrode 10B and the transmissioneasy axis of the other polarizing film 5 were deviated by 12° from 45°and 135°, respectively. Further, the angle made between the longitudinaldirection of the slit 20 formed in the pixel electrode 10R and thetransmission easy axis of one of the polarizing films 5 and the anglemade between the longitudinal direction of the slit 20 formed in thepixel electrode 10R and the transmission easy axis of the otherpolarizing film 5 were deviated by 10° from 45° and 135°, respectively.

FIG. 11 is an equivalent circuit diagram of the liquid crystal display1. As shown in FIG. 11, (m×n) pixel electrodes 10 are arranged to form amatrix in the liquid crystal display 1. An m-number of scanning lines 46extend in the row direction of the pixel electrode 10 and are arrangedin the column direction. On the other hand, an n-number of signal lines49 extend in the column direction of the pixel electrode 10 and arearranged in the row direction.

The scanning line 46 is connected to a scanning line driving circuit 61,and the signal line 49 is connected to a signal line driving circuit 62.Also, the TFT 8 is connected between the signal line 49 and the pixelelectrode 10, and gate of the TFT 8 is connected to the scanning line46. Further, the common electrode 16 is connected to a common electrodedriving circuit 63.

The auxiliary capacitor electrode 44 and the auxiliary capacitor line 47collectively form an auxiliary capacitor C. The auxiliary capacitorelectrode 44 is connected to the pixel electrode 10, and the auxiliarycapacitor line 47 is connected to the common electrode 16.

It was possible to drive the liquid crystal display 1 manufactured bythe method described above by changing, for example, the voltage appliedbetween the pixel electrode 10 and the common electrode 16 within arange of between about 1V and about 4V. Also, the liquid crystal display1 was observed under the state that a voltage of 3.5V was appliedbetween the pixel electrode 10 and the common electrode 16. As a result,observed was a distribution of the transmittance conforming with theshape of the pixel electrode 10. Further, the viewing anglecharacteristics of the liquid crystal display 1 were examined under theconditions described above, with the result that the dependence of thedisplayed color on the observing angle was scarcely recognized, even inthe case where the liquid crystal display 1 was observed in a directionmaking an angle of 80° with the line normal to the main surface of theliquid crystal display 1.

EXAMPLE 2

In this Example, the relationship between the width W₂ of the slit 20formed in the pixel electrode 10 and the transmittance was examinedfirst.

FIG. 12 is a graph exemplifying the relationship between the width W₂ ofthe slit 20 formed in the pixel electrode 10 and the transmittance. Inthe graph of FIG. 12, the voltage applied between the pixel electrode 10and the common electrode 16 is plotted on the abscissa, and thetransmittance is plotted on the ordinate.

Incidentally, the data given in FIG. 12 was obtained in the case wherethe product Δn×d of the refractive index anisotropy Δn relating to thewavelength of 593 nm and the thickness d of the liquid crystal layer 4was 325 nm. To be more specific, curve 71 shown in FIG. 12 denotes thetransmittance in the case where the maximum transmission wavelength is440 nm and the width W₂ of the slit 20 is 4 μm. Curve 72 shown in FIG.12 denotes the transmittance in the case where the maximum transmissionwavelength is 440 nm and the width W₂ of the slit 20 is 5 μm. A curve 73shown in FIG. 12 denotes the transmittance in the case where the maximumtransmission wavelength is 550 nm and the width W₂ of the slit 20 is 4μm. A curve 74 shown in FIG. 12 denotes the transmittance in the casewhere the transmittance in the case where the maximum transmissionwavelength is 440 nm and the width W₂ of the slit 20 is 6 μm. A curve 75shown in FIG. 12 denotes the transmittance in the case where the maximumtransmission wavelength is 550 nm and the width W₂ of the slit 20 is 6μm and the transmittance in the case where the maximum transmissionwavelength is 620 nm and the width W₂ of the slit 20 is 4 μm. Curve 76shown in FIG. 12 denotes the maximum transmission wavelength is thetransmittance in the case where the maximum transmission wavelength is620 nm and the width W₂ of the slit 20 is 5 μm. Further, curve 77 shownin FIG. 12 denotes the transmittance in the case where the maximumtransmission wavelength is 620 nm and the width W₂ of the slit 20 is 6μm.

As shown in FIG. 12, the transmittance is dependent on the width W₂ ofthe slit 20. In other words, it is possible to change the effectiverefractive index anisotropy Δn of the liquid crystal material inaccordance with the width W₂ of the slit 20.

Next, examined were the conditions which permit the transmittance to be40% in the case of applying a voltage of 4.5V between the pixelelectrode 10 and the common electrode 16.

FIG. 13 is a graph showing how the wavelength affects the relationshipbetween the width W₂ of the slit 20 formed in the pixel electrode 10 andthe transmittance. In the graph of FIG. 13, the wavelength is plotted onthe abscissa, and the width W₂ of the slit 20 is plotted on theordinate. Incidentally, a line 81 shown in FIG. 13 denote the conditionswhich permit the transmittance to be 40% in the case of applying avoltage of 4.5V between the pixel electrode 10 and the common electrode16. On the other hand, line 82 shown in FIG. 13 denotes the conditionswhich permit the transmittance to be 40% in the case of applying avoltage of 3.8V between the pixel electrode 10 and the common electrode16.

The data given in FIG. 13 can be utilized in the case where, forexample, it is desirable to make the blue, green and red pixel regionsequal to each other in the transmittance. To be more specific, uniformtransmittance can be achieved by setting the width W₂ of the slit 20formed in each of the pixel electrodes 10B, 10G and 9R at a valueobtained by referring the maximum transmission wavelength of each of theblue, green and red coloring layers 9B, 9G and 9R to the data given inFIG. 13. In other words, the adjustment of the color tone, e.g., thewhite balance, can be achieved by appropriately setting the width W₂ ofthe slit 20 formed in each of the pixel electrodes 10B, 10G and 10R.

Next, prepared was a liquid crystal display 1 by a method similar to themethod in Example 1, except that the construction shown in FIG. 5 wasemployed in the pixel electrode 10. Incidentally, the width W_(2R) ofthe slit 20 was set at 2.7 μm, the width W_(2G) of the slit 20 was setat 4.0 μm, and the width W_(2B) of the slit 20 was set at 6.0 μm. Whatshould be noted is that the width W₂ of the slit 20 was set smaller inthe pixel electrode 10 positioned to face the coloring layer havinglonger maximum transmission wavelength, and the width W₂ of the slit 20was set larger in the pixel electrode 10 positioned to face the coloringlayer having shorter maximum transmission wavelength. In other words,the area ratio of the pixel electrode 10 to a unit area was set higherin the pixel electrode 10 positioned to face the coloring layer havinglonger maximum transmission wavelength, and the area ratio of the pixelelectrode 10 to a unit area was set lower in the pixel electrode 10positioned to face the coloring layer having shorter maximumtransmission wavelength. Also, the width W₁ of the portion of the pixelelectrode 10 sandwiched between the adjacent slits 20, i.e., thecomb-teeth portion, was set at 5 μm.

It was possible to drive the liquid crystal display 1 manufactured bythe method described above by changing, for example, the voltage appliedbetween the pixel electrode 10 and the common electrode 10 within arange of between about 1V and about 5V. Also, the liquid crystal display1 was found to be capable of a good white display. The displaycharacteristics of the liquid crystal display 1 are shown in the tablegiven below:

Uniformity Response Transmissivity of domain time (%) size (ms) Ex. 2 17Good 25 Ex. 3 18 Good 23 Ex. 4 19 Good 29

Also, the liquid crystal display 1 was observed under the state thatvoltage of about 4.5V was applied between the pixel electrode 10 and thecommon electrode 16. As a result, observed was a distribution of thetransmittance conforming with the shape of the pixel electrode 10.Further, the viewing angle characteristics of the liquid crystal display1 were examined under the condition given above, with the result thatthe dependence of the displayed color on the observing angle wasscarcely recognized, even in the case where the liquid crystal display 1was observed in a direction making an angle of 80° with a line normal tothe main surface of the liquid crystal display 1.

EXAMPLE 3

In this Example, prepared was a liquid crystal display 1 in which theconstruction shown in FIG. 5 was employed in the pixel electrode 10 by amethod similar to the method described previously in conjunction withExample 2. In Example 3, however, the width W₁ of the portion of thepixel electrode 10 sandwiched between the adjacent slits 20, i.e., thecomb-teeth portion, was set at 4 μm.

It was possible to drive the liquid crystal display 1 by, for example,changing the voltage applied between the pixel electrode 10 and thecommon electrode 16 within a range of between about 1V and about 5V. Thedisplay characteristics of the liquid crystal display 1 are also shownin the table given above.

Also, the liquid crystal display 1 was observed under the state thatvoltage of about 4.5V was applied between the pixel electrode 10 and thecommon electrode 16. As a result, observed was a distribution of thetransmittance conforming with the shape of the pixel electrode 10.Further, the viewing angle characteristics of the liquid crystal display1 were examined under the condition given above, with the result thatthe dependence of the displayed color on the observing angle wasscarcely recognized, even in the case where the liquid crystal display 1was observed in a direction making an angle of 80° with a line normal tothe main surface of the liquid crystal display 1.

EXAMPLE 4

In this Example, prepared was a liquid crystal display 1 in which aconstruction similar to that shown in FIG. 5 was employed in the pixelelectrode 10 by a method similar to the method described previously inconjunction with Example 2. In Example 4, however, the constructionshown in FIG. 9A was employed in place of forming the slit 20 in thepixel electrode 10. To be more specific, prepared was the pixelelectrode 10 in which the slit 20 was not formed, and a dielectric layer21 was formed to a thickness of 1.4 μm on the pixel electrode 10 suchthat the dielectric layer 21 was patterned like the slit 20.

It was possible to drive the liquid crystal display 1 by, for example,changing the voltage applied between the pixel electrode 10 and thecommon electrode 16 within a range of between about 1V and about 5V. Thedisplay characteristics of the liquid crystal display 1 are also shownin the table given above.

Also, the liquid crystal display 1 was observed under the state thatvoltage of about 4.5V was applied between the pixel electrode 10 and thecommon electrode 16. As a result, observed was a distribution of thetransmittance conforming with the shape of the pixel electrode 10.Further, the viewing angle characteristics of the liquid crystal display1 were examined under the condition given above, with the result thatthe dependence of the displayed color on the observing angle wasscarcely recognized even in the case where the liquid crystal display 1was observed in a direction making an angle of 80° with a line normal tothe main surface of the liquid crystal display 1.

Additional advantages and modifications will readily occur to thoseskilled in the art. Therefore, the present invention in its broaderaspects is not limited to the specific details and representativeembodiments shown and described herein. Accordingly, variousmodifications may be made without departing from the spirit or scope ofthe general inventive concept as defined by the appended claims andtheir equivalents.

1. A liquid crystal display, comprising: an array substrate with firstto third pixel electrodes on a main surface thereof; a counter substratewith a common electrode that faces the first to third pixel electrodeson a main surface thereof; a liquid crystal layer sandwiched between thearray and counter substrates; and a color filter supported by one of thearray and counter substrates and comprising first to third coloringlayer facing the first to third pixel electrodes, respectively, whereinthe display is configured to form first and second optical regionsdifferent from each other in electric field intensity in each of firstto third pixel regions between the common electrode and the first tothird pixel electrodes when voltage is applied therebetween, the firstand second optical regions extending in a direction that is parallel tothe liquid crystal layer and alternately arranged in a direction thatcrosses a longitudinal direction of the first optical region in each ofthe first to third pixel regions, and wherein the first pixel region isdifferent in a shape of the first and/or second optical region from thesecond and third pixel regions.
 2. The display according to claim 1,wherein the first pixel region is different in width of the first and/orsecond optical region from the second and third pixel regions.
 3. Thedisplay according to claim 1, wherein each of the first to third pixelregions comprises at least two domains each including the first andsecond optical regions, the longitudinal direction of the first opticalregion in one of the domains and the longitudinal direction of the firstoptical region in the other of the domains being parallel and/orperpendicular to each other, and the domains being different from eachother in director of liquid crystal molecules, which is contained in theliquid crystal layer, on application of voltage.
 4. The displayaccording to claim 1, wherein each of the first to third pixel electrodeis provided with a slit at a position corresponding to the secondoptical region.
 5. The display according to claim 4, wherein each of thefirst to third pixel electrodes is a comb-shaped electrode.
 6. Thedisplay according to claim 1, further comprising polarizers on outersurfaces of the array and counter substrates, wherein the longitudinaldirection of the first optical region in each of the first to thirdpixel regions crosses a transmission easy axis of one of the polarizersat an angle of 45°.
 7. The display according to claim 1, wherein thecolor filter comprises blue, green and red coloring layers as the firstto third coloring layers.
 8. The display according to claim 1, furthercomprising vertical alignment layers on the first to third pixelelectrodes and on the common electrode, respectively, wherein the liquidcrystal layer contains a liquid crystal material with negativedielectric anisotropy.
 9. The display according to claim 1, wherein thecommon electrode is a flat continuous layer.
 10. The display accordingto claim 1, wherein the color filter is supported by the arraysubstrate.
 11. A liquid crystal display, comprising: an array substratewith first to third comb-shaped electrodes on a main surface thereof; acounter substrate with a common electrode that faces the first to thirdcomb-shaped electrodes on a main surface thereof; a liquid crystal layersandwiched between the array and counter substrates; and a color filtersupported by one of the array and counter substrates and comprisingfirst to third coloring layer facing the first to third comb-shapedelectrodes, respectively, wherein the first comb-shaped electrode isdifferent in shape and/or orientation from the second and thirdcomb-shaped electrodes.